This invention relates to isobutylene-based polymers containing enchained cyclic diolefin moieties as well as certain functional groups which allow chemical and/or physical through curing, while the surface may be air dried owing to the cyclic unsaturation.
Isobutylene-based polymers containing relatively low (less than about 10%) enchained cyclic diolefin and exhibiting excellent ozone resistance are well known in the art. See U.S. Pat. Nos. 2,577,822, 2,521,359, 2,626,940 and 3,903,039. Isobutylene-based polymers containing greater than 10 mol percent cyclic diolefin are also known in the art. See U.S. Pat. No. 2,521,359 and Ind. Eng. Chem. Prod. Res. & Dev. 10, 279(1971). Also see U.S. Pat. No. 3,496,129 which discloses a non-elastomeric cyclic diolefin-containing air dryable coating.
Although the above-mentioned polymers have been known for a number of years, they have never been commercialized, partly owing to polymerization problems such as reactor fouling, poor catalyst efficiency, difficulties in handling the reactive cyclic diolefins and their severe molecular weight depressing effect; but the major reason for their lack of commercialization has been that attractive properties for practical applications have not been developed.
Butyl-type polymers in general possess many desirable properties for surface coatings. For example, they have low permeability, excellent chemical resistance, good environmental resistance, low water absorption, permanent flexibility and low surface energy to provide good substrate wetting and physical adhesion. Despite these properties, low molecular weight butyl-type polymers have had limited commercial success owing to: (1) they can only be used in a two part system (i.e., chemical curatives are required); (2) the only ambient condition cure system available is based on quinoid compounds which produce a dark color and are staining so that ambient cured light colored coatings are not possible; and (3) the coatings have a relatively high degree of surface tack and become even tackier during exposure so that a high dirt pick-up is always encountered. Despite extensive work of researchers with both cyclic and acyclic butyl-type polymers the desired combination of properties has heretofore never been realized.